Sweet Flag
Acorus calamus
📖 About this plant
A distinctive, grass-like perennial valued for its aromatic, sweetly scented rhizomes and bold, sword-shaped, bright green or variegated leaves that fan outward from a central crown. The leaves have a pleasant, spicy fragrance when crushed. An excellent choice for water gardens, pond margins, rain gardens, and boggy areas. The golden-variegated cultivar ‘Variegatus’ is especially popular for its bright color.
🧑🌾 Care requirements
Partial shade to full sun (3-6 hrs)
Consistently moist
High (60-80%)
5-28°C
Moist to wet, organically rich soil; thrives at pond edges, in bog gardens, and shallow water up to 15 cm deep
Balanced slow-release fertilizer in early spring; benefits from compost or manure top dressing
🌐 Common Names
📋 Plant facts
- 🌍 Origin
- Widespread across temperate and subtropical Northern Hemisphere — Europe, Asia, and North America; ancient medicinal and ceremonial plant
- 📏 Max height
- 30-90 cm
- 📐 Spread
- 30-60 cm
- 🕰️ Bloom time
- Late Spring - Summer
- 🎨 Bloom color
- Green, Yellow
- 🍃 Foliage color
- Green, Yellow Striped
- ⏳ Lifespan
- Perennial
- 📈 Growth rate
- Moderate
- ☠️ Toxicity
- Contains beta-asarone, which is classified as a possible carcinogen; rhizomes traditionally used medicinally but internal use not recommended — handle with care
- 🌱 Propagation
- Division of rhizomes in early spring; rhizome cuttings laid on moist soil or water
🛡️ Health & Safety
Common issues
- Rust disease
- Leaf spot
- Rhizome rot from overwatering
- Spider mites
💡 Care tips
- Aromatic grass-like plant that thrives in wet boggy areas
- Iris-like yellow-green flower spikes appear in late spring
- Roots were historically used in herbal medicine
- Grows well at pond edges or in rain garden areas



